DESCRIPTION: (From applicant's Abstract): The major goal of the proposed research is to define,for amino acid taste reception, the molecular mechanisms that link stimulus-receptor interaction with subsequent ionic events in the receptor cells. Research will focus on the study of taste transduction in two model systems: catfish (L-Arg) and mice (MSG). Voltage-dependent and stimulus-regulated changes in membrane conductance will be examined in isolated receptor cells using whole-cell recording techniques and stimulus-induced changes in intracellular calcium levels will be monitored in real time using fura-2 and video microscopy. Single-channel properties will be studied in excised patches and planar bilayers into which taste membrane fragments have been incorporated. L-Arg and MSG receptors, that the investigator hopes will be cloned by another investigator, will be functionally expressed in heterologous systems and compared with native receptors in terms of specificity, sensitivity, ion selectivity, channel kinetics and pharmacology. It is hoped that these experiments will provide a comprehensive description of amino acid taste signal transduction in the catfish model, as well as the basis for similar studies in mammalian taste cells.